In various wired and wireless communication systems the performance of a receiver is degraded by interfering signals originating from a transmitter. Methods for suppressing such interference are known in the art. For example, U.S. Pat. No. 7,672,447 describes an echo canceller that reduces an echo signal produced when the transmitted signal leaks back into the receiver via a hybrid. The echo canceller estimates the echo signal from the transmitted signal, and then the estimated echo signal is subtracted from the received signal. In practice, the echo path channel in a DMT-modem is much longer than the cyclic prefix, and therefore, the received echo signal will be subjected to both ISI (inter-symbol-interference) and ICI (inter-carrier-interference). A traditional echo canceller, designed for a xDSL-modem, uses either a time domain adaptive FIR-filter or a combined echo canceller implemented in both time and frequency domain. A matrix-based adaptive echo canceller is implemented in the frequency domain.
U.S. Patent Application Publication 2017/0237492 describes achieving full duplex bidirectional transmission across coaxial cable in a hybrid fiber-coaxial cable TV network. Some preferred systems and methods will attenuate reflections propagated within the coaxial cable. Other preferred systems may echo-cancel reflections propagated within the coaxial cable.
U.S. Patent Application Publication 2017/0019241 describes a communication system comprising a media access control (MAC) scheduler in a cable network, and a full band transceiver. The MAC scheduler implements a two-dimensional transmission-reception (T-R) coordination scheme among a plurality of cable modems in the cable network. The cable modems are categorized into interference groups for facilitating full duplex communication in the cable network across the frequency range. The full band transceiver implements an adaptive interference cancellation scheme, which suppresses at a receiver a signal transmitted by a transmitter.
An international telecommunications standard, referred to as “Data Over Cable Service Interface Specification” (DOCSIS) that was developed by CableLabs and contributing companies, specifies the transfer of high-bandwidth data over existing cable TV (CATV) systems. In 2017, a Full Duplex (FDX) version of DOCSIS version 3.1 has been announced, in which at least part of the spectrum of the cable plant can be used simultaneously in both upstream and downstream directions. The physical layer of the DOCSIS 3.1 standard, including FDX, is specified, for example, in Annex F of the specifications “Data-Over-Cable Service Interface Specifications DOCSIS® 3.1, Physical Layer Specification,” CM-SP-PHYv3.1-I13-171220, December 2017.